CAFE Electric Aircraft Symposium Set For May 1

On 5/8/2015 2:30 PM, Larry Dighera wrote:

Personally, I find the whole argument on hydrogen as a replacement
for gasoline a joke.
The limited research I conducted years ago seemed to suggest that there wasn't
much else that approached the energy density of gasoline/kerosene. So, while
perhaps not ideal, hydrogen is a somewhat viable alternative to petroleum, that
has the potential to provide efficiencies several times better than the ~30%
efficiency obtained with internal combustion power plants. If you consider
that only one third the fuel will be required to achieve the current
performance, the numbers begin to make more sense.

With 70% of the energy blowing out the exhaust as heat, internal combustion
engine efficiency is comparable to an incandescent lamp that consumes ~90% of
its energy usage to produce heat, and only ~10% to produce light. LEDs, on the
other hand, can be 90% more efficient than tungsten filament lamps, and they
last many times longer too.

Simply put, the problem with using hydrogen as a fuel is that we have no
natural source of it in unattached gaseous form. So we have to MAKE
hydrogen by reforming it from natural gas, or by some even more
energy-hungry method such as electrolysis of water.

So while hydrogen can be used as a fuel, it is not a SOURCE of energy
such as natural gas or gasoline is. Hydrogen is only a CARRIER of
energy (much like our electrical utilities are a carrier of energy, not
a source of energy). In the process of converting "something" to
hydrogen, you never have 100% efficiency, so on a whole-cycle macro
scale the efficiency picture of hydrogen can look pretty dismal.

Also, an article might extol the clean burning properties of hydrogen in
an engine or fuel cell, while failing the mention the pollution produced
by the manufacture of hydrogen.

Vaughn wrote:
On 5/8/2015 2:30 PM, Larry Dighera wrote:

Personally, I find the whole argument on hydrogen as a replacement
for gasoline a joke.
The limited research I conducted years ago seemed to suggest that there wasn't
much else that approached the energy density of gasoline/kerosene. So, while
perhaps not ideal, hydrogen is a somewhat viable alternative to petroleum, that
has the potential to provide efficiencies several times better than the ~30%
efficiency obtained with internal combustion power plants. If you consider
that only one third the fuel will be required to achieve the current
performance, the numbers begin to make more sense.

With 70% of the energy blowing out the exhaust as heat, internal combustion
engine efficiency is comparable to an incandescent lamp that consumes ~90% of
its energy usage to produce heat, and only ~10% to produce light. LEDs, on the
other hand, can be 90% more efficient than tungsten filament lamps, and they
last many times longer too.

Simply put, the problem with using hydrogen as a fuel is that we have no
natural source of it in unattached gaseous form. So we have to MAKE
hydrogen by reforming it from natural gas, or by some even more
energy-hungry method such as electrolysis of water.

So while hydrogen can be used as a fuel, it is not a SOURCE of energy
such as natural gas or gasoline is. Hydrogen is only a CARRIER of
energy (much like our electrical utilities are a carrier of energy, not
a source of energy). In the process of converting "something" to
hydrogen, you never have 100% efficiency, so on a whole-cycle macro
scale the efficiency picture of hydrogen can look pretty dismal.

Also, an article might extol the clean burning properties of hydrogen in
an engine or fuel cell, while failing the mention the pollution produced
by the manufacture of hydrogen.

If you burn hydrogen in an engine, you get lots of NOX byproducts, i.e.
smog, because air is mostly nitrogen and hydrogen has a very high
flame temperature.

Fuel cells do not have that problem as the temperatured involved are
much lower.



--
Jim Pennino

On 5/9/2015 4:32 PM, wrote:

If you burn hydrogen in an engine, you get lots of NOX byproducts, i.e.
smog, because air is mostly nitrogen and hydrogen has a very high
flame temperature.

Fuel cells do not have that problem as the temperatured involved are
much lower.



Yes, but my point was that you are still left with the problem of the
pollution and greenhouse gas generated by the production of your "clean"
hydrogen fuel.

Besides, for at least the last 30 years, mass consumer fuel cells have
been "just around the corner". Even if they suddenly became practical
and economical, we would still be left with the huge problems involved
in producing and distributing hydrogen.

You can wave your arms and talk about fuel cells all day, but the
problems with hydrogen won't go away. Hydrogen is not an energy source.
To make hydrogen, you make pollution.

Vaughn wrote:
On 5/9/2015 4:32 PM, wrote:

If you burn hydrogen in an engine, you get lots of NOX byproducts, i.e.
smog, because air is mostly nitrogen and hydrogen has a very high
flame temperature.

Fuel cells do not have that problem as the temperatured involved are
much lower.



Yes, but my point was that you are still left with the problem of the
pollution and greenhouse gas generated by the production of your "clean"
hydrogen fuel.

Besides, for at least the last 30 years, mass consumer fuel cells have
been "just around the corner". Even if they suddenly became practical
and economical, we would still be left with the huge problems involved
in producing and distributing hydrogen.

You can wave your arms and talk about fuel cells all day, but the
problems with hydrogen won't go away. Hydrogen is not an energy source.
To make hydrogen, you make pollution.

And my point was if you BURN hydrogen, you make pollution.



--
Jim Pennino

wrote in :

Vaughn wrote:
On 5/9/2015 4:32 PM, wrote:

If you burn hydrogen in an engine, you get lots of NOX byproducts,
i.e. smog, because air is mostly nitrogen and hydrogen has a very high
flame temperature.

Fuel cells do not have that problem as the temperatured involved are
much lower.



Yes, but my point was that you are still left with the problem of the
pollution and greenhouse gas generated by the production of your
"clean" hydrogen fuel.

Besides, for at least the last 30 years, mass consumer fuel cells have
been "just around the corner". Even if they suddenly became practical
and economical, we would still be left with the huge problems involved
in producing and distributing hydrogen.

You can wave your arms and talk about fuel cells all day, but the
problems with hydrogen won't go away. Hydrogen is not an energy
source.
To make hydrogen, you make pollution.

And my point was if you BURN hydrogen, you make pollution.

You are BOTH right.

And a similar argument can be made for going all electric. How
do you make electricity? Right now, most of it is made by BURNING
hydrocarbons.

Moving to electric powered vehicles only shifts the location of
the burning from the vehicle to the electric power plant.

The only way to make electric vehicles viable from a 'pollution
elimination' point of view is to ALSO generate the electricity
from some other method than burning hydrocarbons.

As Vaughn pointed out, we have to find an alternate SOURCE of
energy, not an alternate medium by which to store it. Hydrocarbons
are a source of energy. We get more energy out of hydrocarbons
than we put in to extract it. We don't have to make it. Although
there is the argument about how much is left.

The problem is finding a viable alternate source of energy to
replace hydrocarbons. Ones that can produce energy on par with,
and for future growth eventually exceed the scale of what we get
out of hydrocarbons.

And then there's the whole problem of upgrading the power grid to
handle everyone plugging in their e-car's without the wires glowing.
The alternative to that may well be distributed energy generation.

Replacing hydrocarbons for transportation use is not a simple
or singular problem. At the risk of sounding cliche, it will
require a paradigm shift in the way energy is produced, distributed,
and consumed, and it will have to be adopted by everyone to make
it work.

Brian
--
http://www.earthwaves.org/forum/index.php - Earth Sciences discussion
http://www.skywise711.com - Lasers, Seismology, Astronomy, Skepticism
Sed quis custodiet ipsos Custodes?

In article , ,
says...

Vaughn wrote:
On 5/9/2015 4:32 PM, wrote:

If you burn hydrogen in an engine, you get lots of NOX byproducts, i.e.
smog, because air is mostly nitrogen and hydrogen has a very high
flame temperature.

Fuel cells do not have that problem as the temperatured involved are
much lower.



Yes, but my point was that you are still left with the problem of the
pollution and greenhouse gas generated by the production of your "clean"
hydrogen fuel.

Besides, for at least the last 30 years, mass consumer fuel cells have
been "just around the corner". Even if they suddenly became practical
and economical, we would still be left with the huge problems involved
in producing and distributing hydrogen.

You can wave your arms and talk about fuel cells all day, but the
problems with hydrogen won't go away. Hydrogen is not an energy source.
To make hydrogen, you make pollution.

And my point was if you BURN hydrogen, you make pollution.



Water is pollution?

I think you either need to get your chemistry right, or define
"hydrogen" - or perhaps, what you are burning. Hydrocarbons?

--
Duncan.

Dave Doe wrote in
:

Water is pollution?

I think you either need to get your chemistry right, or define
"hydrogen" - or perhaps, what you are burning. Hydrocarbons?

Burning hydrogen with pure oxygen produces only water vapor.
For example, LH2 and O2 rocket engines such as the Shuttle's.

Burning hydrogen with 'air' also produces other compounds,
including nitrous oxides (smog, harmful to humans). 'Air' is
not pure oxygen.

Check your chemistry.

Brian
--
http://www.earthwaves.org/forum/index.php - Earth Sciences discussion
http://www.skywise711.com - Lasers, Seismology, Astronomy, Skepticism
Sed quis custodiet ipsos Custodes?

In article , ,
Skywise says...

Dave Doe wrote in
:

Water is pollution?

I think you either need to get your chemistry right, or define
"hydrogen" - or perhaps, what you are burning. Hydrocarbons?

Burning hydrogen with pure oxygen produces only water vapor.
For example, LH2 and O2 rocket engines such as the Shuttle's.

Burning hydrogen with 'air' also produces other compounds,
including nitrous oxides (smog, harmful to humans). 'Air' is
not pure oxygen.

Check your chemistry.

Oh I have! Hence the question. I'm sure you've heard of Oxyhydrogen
plants (as in Oxyacetalene plants).

--
Duncan.

Dave Doe wrote:
In article , ,
says...

Vaughn wrote:
On 5/9/2015 4:32 PM, wrote:

If you burn hydrogen in an engine, you get lots of NOX byproducts, i.e.
smog, because air is mostly nitrogen and hydrogen has a very high
flame temperature.

Fuel cells do not have that problem as the temperatured involved are
much lower.



Yes, but my point was that you are still left with the problem of the
pollution and greenhouse gas generated by the production of your "clean"
hydrogen fuel.

Besides, for at least the last 30 years, mass consumer fuel cells have
been "just around the corner". Even if they suddenly became practical
and economical, we would still be left with the huge problems involved
in producing and distributing hydrogen.

You can wave your arms and talk about fuel cells all day, but the
problems with hydrogen won't go away. Hydrogen is not an energy source.
To make hydrogen, you make pollution.

And my point was if you BURN hydrogen, you make pollution.



Water is pollution?

I think you either need to get your chemistry right, or define
"hydrogen" - or perhaps, what you are burning. Hydrocarbons?

Air is 78% nitrogen.

Air is used as the oxidizer in an engine.

At high temperatures, i.e. inside an engine, the nitrogen combines
with the excess oxygen to produce NOx; mostly NO and NO2.

It does not matter what is actually "burning", it is the temperature
that causes the reaction and hydrogen has a very high flame temperature.

As hydrocarbons as a rule do not contain nitrogen, where do you think
the NOx emmisions come from?


--
Jim Pennino